The present invention is directed to a filter element for use in a container with a central pipe which is closed along its length and provided with a lower opening, as well as to a method of filtration.
A filter element comprising a central pipe for draining off a filtrate, which central pipe is closed along its entire length and is only open at the top and bottom, is known from CH-A-631 352. The known filter element is suitable for a filtration for separating fine particles from a suspension and for a residual volume filtration, but does not satisfy the imposed requirements under extreme conditions in which filtration which is free of foreign matter is required. In this case, foreign matter is understood to mean the finest particles which can be disengaged, e.g., from multiple-filament woven textile filters and which must be removed, e.g. in the production of serum.
Filter cartridges which are woven from monofilament, particularly metal wire, are known per se. However, they have the disadvantage that dynamic cleaning is not possible with them, and an attached filter cake can therefore be removed only with great difficulty and incompletely. The woven wire fabrics are rigid and are permeable to air to a relatively great degree. In order to detach a dry filter cake and subsequently discharge it from a filter container, greater quantities of gas in sudden bursts are required than is the case when using textile filter.